The aim of this study is to gain a better understanding of transcriptional regulation. Elucidating the mechanisms by which genes are regulated is one of the fundamental questions in molecular biology and has broad implications in our understanding of the normal functional processes in the cell, but also and perhaps more significantly to systems that malfunction in diseased or cancerous cells. The TFIID complex is the central unit which integrates all signals in the RNA pol II transcription apparatus. Using the power of yeast genetics will allow a detailed and more rapid analysis of transcriptional control to be performed, the results of which are directly applicable to the more complex mammalian system. This study aims to elucidate the assembly of the TFIID complex, the essential domains in the interacting proteins and also to identify interacting proteins- which should consist of both yeast TAFs and unknown activators and coactivators.